Thanks Kent and Gary,
Yeah they claim E100G has lower D-min giving the whiter images. Definetely I will give it a go together with Velvias.
I don't know which I will like more because E100G has closer to the natural colours whereas Velvia has higher saturation.
Good thing is that E-6 processing in Korea and Japan is quite cheap ($3 for 120 roll) compared to Australia ($12) so I might try Provia as well.
I'll be using my reliable Mamiya 645 Pro with AE finder so the camera side should be fine.